I dont have enough plays under my belt to answer this question. The consensus at the FFG discussion board is that the human torch requires some nerfing because he unbalances the game in favor of the F4.

Check out his combat special ability. Any time he rolls 4 or more hits, he inflicts a KO. If he's fighting someone with no defense, he can inflict 2 KOs before the villian gets the opportunity to even attack.

It's not an over-powering ability, it's just that he probably costs less than he should.